This invention relates to a method and device for processing a slaughtered bird which is hung by its legs from a hook of a moving conveyor. Methods and devices of this nature are generally known.
A special processing operation carried out on a slaughtered and eviscerated bird is a partial processing operation in which an automatic or semi-automatic processing device is used to obtain bird parts which are each of substantially identical weight or contain an equal amount of meat, irrespective of the body part (such as breast, wing, thigh, drumstick) which the bird part comprises. Since the amount of meat per bird part is relatively limited, the division must be carried out as accurately and reproducibly as possible, in order to keep differences in weight or amount of meat between the different bird parts within predetermined limits. A division which satisfies this requirement can only be carried out if the bird is accurately positioned in the processing device. The known methods and devices are not entirely satisfactory with regard to this point.
EP-B-0,033,177 describes a device for dividing a bird into nine parts, each of substantially the same weight. To this end, the bird has to be manually arranged on a positioning support which acts on the bird at the location of the ankle joints and the wings, and also supports the bird at the sides of the body, the top of the thighs, behind the spinal column and on the back. Then, various blades are used to automatically cut through the carcass, the breast and a first wing being cut off successively, and then a body longitudinal-halving cut being made, the other wing and the complete legs being cut off, and the drumsticks being cut free from the thighs.
A drawback of the device described in EP-B-0,033,177 is that it is not suitable for picking up and processing birds which have been supplied in a conveyor, such as an overhead suspension conveyor, without human intervention; the birds have to be arranged manually on the positioning supports. Furthermore, the bird is not optimally positioned on the positioning support.
EP-A-0,545,040 describes a device for cutting off a breast part of a bird, the wings already having been removed from the bird. The bird is hung by its legs from a hook and is internally supported by means of a mandrel which substantially fills the body cavity and causes the breast of the bird to project outwardly by exerting pressure on the ribs of the chest. On the outside of the carcass, there is a pivotable retention plate which interacts with an opposite surface of the mandrel and, on the side which is to face the mandrel, comprises a projection which clamps the clavicle of the bird against the mandrel. The retention plate also supports the shoulders of the bird. After the bird has been fixed in position in this way, firstly a stationary blade is used to make a transverse guide cut, at an angle to the carcass surface, in the abdomen of the bird, between the pelvis and the breastbone. Then, a rotating blade is used to make a transverse cut, at an angle to the carcass surface, in the breast of the bird, in order to separate the breast from the neck, shoulders and upper back of the bird. Finally, in the path of the transverse guide cut, a second cut is made with a rotating blade, in order to separate the breast from the pelvis and the lower back of the bird.
A drawback of the device according to EP-A-0,545,040 is that it is necessary for a voluminous mandrel to be introduced into the body cavity of the bird in order to make the desired cuts, but the positioning of the breast of the bird is not optimum for a cut/cuts to be made, as a result of the breast being supported by the mandrel in the area of the ribs. Also, since the positioning of the breast is not optimum, asymmetric breast parts are often cut off, which are increasingly unacceptable for purchasers of the breast pieces.
An object of the invention is to improve the positioning of the bird, in particular of its breast, in order for breast-related processing operations to be carried out. It is also an object to optimize the breast cut(s).
A further object of the invention is to optimize the way in which the wings and the legs of the bird are cut off.
Another object of the invention is to provide the option for the division of the bird to take place completely automatically.
In order for one or more of the above-mentioned objects to be achieved, the method according to the invention for carrying out at least one processing operation on a slaughtered bird which is hung by its legs comprises the steps: providing a conveyor with at least one hook for hanging and conveying the bird; providing a processing device with a processing area for carrying out the at least one processing operation on the bird; using the conveyor to convey the bird towards and into the processing area of the processing device; positioning the bird in the processing area of the processing device by externally supporting the bird at at least two locations, selected from the group of locations which comprises the back, the sternum, the area of the clavicle, the wings and the sides of the bird; and carrying out the at least one processing operation in the processing device in the area of the breast of the bird.
Alternatively, the step of positioning the bird in the method according to the invention comprises the step of internally supporting the bird on that side of the sternum which faces towards the abdominal cavity of the bird.
In the two ways mentioned above, it is possible to obtain a very accurate, stable and reproducible positioning of the bird for a wide variety of breast-related processing operations, such as: cutting off part of the breast; removing the skin from the breast; deboning the breast; dividing the carcass into a front half and a rear half; separating the wings from the carcass; and injecting a substance into the breast.
An additional processing operation for a breast-related processing operation is, for example, making a transverse incision in the abdomen below the sternum. In this case, use is preferably made of a sternum support element which acts on that side of the sternum which is directed towards the abdominal cavity of the bird, in the area of the free end of the trabecula mediana. Since this part of the sternum is accessible to the sternum support element from the outside of the bird, this is regarded as external support of the bird. The sternum support element, which may, for example, comprise a guide rail which extends in the path of the sternum, ensures that during the transverse incision the sternum is kept out of the path of the cutting means used, such as a rotating knife.
A similar external sternum support element in the form of a guide which extends in the path of the sternum can be used for cutting off part of the breast, comprising part of the trabecula mediana and each trabecula intermedia. This sternum support element also preferably acts on the sternum in the area of the free end of the trabecula mediana.
Preferably, another sternum support element is introduced into the abdominal cavity of the bird from a neck opening or drawing opening of the bird which has been made in an earlier processing stage, in order to reach the desired location in the area of the sternum, in particular the area of the rostrum sterni or the area of the ventricle.
In a preferred embodiment, the latter sternum support element comprises an arm which can move in a controllable manner, a free end of the arm being adapted to engage the side of the sternum facing the abdominal cavity. In order to make it easier to introduce the sternum support element into the body of the slaughtered animal, a first part of the arm may be pivotably connected to a second part of the arm, in which case the first part can be oriented, in a controllable manner, both substantially in line with the second part and at an angle with respect thereto, for example an angle of substantially 90xc2x0.
In an expedient embodiment, the means for positioning the sternum form a single unit with means for positioning the clavicle, so that positioning inaccuracies resulting from tolerances in the tools used are reduced to a minimum.
Preferably, a clavicle support element acts on the concave side of the clavicle, to which end the clavicle support element advantageously comprises a substantially L-shaped arm with a short limb and a long limb, the short limb being intended to engage the concave side of the clavicle. In this case, for optimum positioning of the clavicle, the arm is preferably moved such that the angle between the longitudinal axis of the short limb and a horizontal plane when the short limb is engaging the clavicle is larger than when it is at a distance from the clavicle. As a result, the sternum, which is connected to the clavicle, is pressed against a sternum support element.
Positioning of the body of the bird for the purpose of a partial processing operation comprises the step of: moving the wings with respect to the body, substantially in a direction away from the hips. For this purpose, it is possible to provide a pair of forks which can be displaced in a controllable manner in the vertical direction and each have a pair of downwardly directed limbs, the distance between the limbs of each fork substantially corresponding to a transverse dimension of a wing. Each of the forks is intended to be placed between the hips and the shoulders of the bird, and the forks can pivot, in a controllable manner, between a first angular position, in which the distance between the ends of the pairs of limbs substantially corresponds to the width of the body of a bird between the hips and the shoulders, and a second angular position, in which there is a greater distance between said ends of said pairs of limbs than in said first angular position. In the first angular position of the forks, the body of the bird is positioned between the forks. Then, the forks are moved downwards, with the humerus of each wing moving in between the limbs of a fork. At the same time, or next, the forks are pivoted into their second angular position, with the result that the body of the bird is stretched as a result of a tensile force which is thus exerted between the legs and the wings. This makes it easier to carry out the cutting processing operations on the body.
In a preferred embodiment, the forks are arranged on a common body member, which body member may also comprise a pivotable plate, at least a section of which is intended to be brought into contact with the back of the bird in order to position the back.
In another preferred embodiment, the positioning means comprise a pair of wing support elements which can be displaced in a controllable manner in the vertical direction and each have a downwardly directed hook-like end, which wing support elements are each intended to be placed between the hips and the shoulders of the bird and can pivot, in a controllable manner, between a first angular position, in which their hook-like ends are directed downwards, and a second angular position, in which said ends hook around the wings and are directed substantially towards the back of the bird.
Preferably, while a part of the breast is being cut off, the breast of the bird is pushed away substantially parallel to the plane of the cut and in the direction in which the cut is being made, in particular by means of at least one belt conveyor. In this way, an optimum cut for obtaining a symmetrical breast part of the desired dimensions is obtained both in the method and device according to the invention, but also in other devices, such as devices according to the prior art. The conveying speed of the belt conveyor is preferably selected in such a way that it is greater than or equal to the conveying speed of the conveyor. An optimum action of the conveyor on the breast part which is to be cut off is obtained if the material of the belt is resilient.
In the prior art, the connections between the legs and the body of the bird ensure that cuts for separating the legs from the bird cannot be carried out optimally, since the mobility of the legs with respect to the body is limited. If firstly a transverse incision is made in the abdomen itself, or the breast part is cut off, and the legs are only separated from the body after this, the legs can be directed much more easily and, in addition, are much more accessible to knives in the hip area. Before the legs are cut off the body of the bird, the hips of the bird can be dislocated, which can be easily achieved as a result of the easier manipulation of the legs after the breast part has been cut off the bird in accordance with the invention. Other advantages are obtained during any further processing operations, such as roasting, frying, coating with breadcrumbs and marinating, since undesirable cavities in which substances such as water, breadcrumbs and marinade could accumulate, are avoided.
According to the invention, the dislocation of the hips of the bird which is suspended by its legs from a hook of a moving conveyor comprises the steps of: placing a leg support element against each leg on the side of the leg which faces towards the breast side of the bird; placing a hip support element against each hip on the side of the hip which faces the back of the bird; and exerting oppositely directed forces on the bird by means of the leg support element and the hip support element in order to dislocate the hip joints. Such a method can be carried out completely automatically very well, both in combination with other processing operations on the bird and independently of such operations.
Preferably, the legs are spread apart by exerting oppositely directed forces in the hollows of the knees of the legs, and the leg support element engages the leg in the area of the drumstick. Dislocating the hips of a bird which is suspended from a hook of a moving conveyor can be carried out most easily if the legs of the bird are situated one behind the other, as seen in the conveying direction of the conveyor. In this case, the hip dislocating forces are exerted in a direction which is substantially transverse with respect to the direction of movement of the conveyor while the bird is being conveyed.
In a preferred embodiment, the leg support element and/or the hip support element comprise a guide which runs substantially parallel to or at a small angle to the conveying direction of the conveyor. It is thus extremely simple to obtain an effective hip dislocating device.
In another preferred embodiment, the means for supporting the hip comprise a pair of pins, of which the areas between the ends thereof are designed so as to engage the hips. In particular, the longitudinal axis of the pins is oriented substantially vertically. The use of the pins offers the advantage that the dislocation can be controlled separately for each of the two hips of a bird. As an alternative to pins, it is also possible for the hip support means used to be a pair of wheels, the circumferential sides of which are designed to engage the hips.
According to the invention, the wings of the bird, including a part of the breast or the back of the bird, can be cut off optimally, both in combination with other partial processing operations and independently from such operations, by means of a rotating knife, the corresponding shoulder joint of the bird moving past the knife near the underside thereof, and the active part of the knife moving in substantially the same direction as the shoulder joint. Advantageously, the legs of the bird are in this case situated next to one another, as seen in the conveying direction of the conveyor. The particular manner of cutting allows the wings of the bird to be guided past the knife in a substantially natural position of the wings.
The claims and advantages will be more readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawings in which like reference symbols designate like parts.